Transformer core clamping means



July 27, 1937. ASTQN I 2,087,906

TRANSFORMER CORE CLAMPING MEANS Filed March 13, 1935 3 SheetsSheet l INVENTOR JOHN R. GASTON ATTORNEY July 27, 1937. J. R. GASTON 2,087,906

TRANSFORMER CORE CLAMPING MEANS Filed March 13, 1935 3 Sheets-Sheet 2 INVENTOR Joy/v R GAsTo/v a iMW ATTORNEY 3 Sheets-Sheet 5 J. R. GASTON TRANSFORMER CORE CLAMPING MEANS Filed March 15, 1955 July 27, 1937.

ATTORNEY W m 9 2 W W 1 J x Vm wh V A M 7i w \4 :i. m 4 W N E i w, T, W i 5 5 Q Q a m A W W i f; E :1 ill 5 m Patented July 27, 1937 UNITED STATES PATENT OFFICE John R. Gaston, East Orange, N. J., assignor to American Transformer Company, Newark, N. J.

Application March 13,

8 Claims.

This invention relates to the construction of a transformer and more particularly to the details of the core assembly.

In prior transformer constructions, the windings must be inserted when the lamination stack is in a more or less loose. condition, whereby the laminations shift in their position, giving an irregular mechanical assembly leading to increased core losses and exciting current, together with greater expense in trying to get a satisfactory assembly.

It is therefore the principal object of my invention to provide a core assembly which will give as nearly perfect an assembly of core laminations as possible, thereby reducing the core losses to a minimum, as well as the exciting current loss to a minimum, and reducing the expense of assembly.

Another object of my invention is to provide a more rigid core. assembly construction by which the entire transformer may be handled without damaging the winding.

Another object 01 my invention is to provide a construction in which the windings may be later removed for repair purposes should they become injured or burned out for any reason, without disturbing the entire core. By the construction to be hereinafter described, it will be seen that the transformer may be lifted bodily out of the casing by the special means provided therefor, and by removing the top clamps and the top laminations, the windings may be replaced.

Another object of my invention is to provide an improved means of anchoring the transformer per se within the casing.

Another object of my invention is to provide a core construction using I-shaped laminations, which is the most economical because there is no die charge or waste material, and in which full advantage can be taken of the grain of the material in cutting the individual lamination pieces, which are cut so that the grain of the material is in the direction of the flow of magnetic flux, thereby giving a minimum amount of core loss without a proportionate increase in exciting current.

A further object of my invention is to provide a core construction which will permit a better flow of varnish between-the laminations than in prior constructions, thereby further reducing the core losses.-

Another object of my invention is to provide a core construction which will produce a totally lighter assembly than with'the transformer cores 1935, Serial No. 10,849

of the conventional I or E type held with the conventional type of clamps.

These and other objects will be apparent to one skilled in the art, after a study of the annexed drawings and specification, wherein:

Figure l is a part-sectional and part-elevational end view of a transformer incorporating my invention, mounted within a casing, the leads from the winding as well as the cover of the transformer casing being omitted.

Figure 2 is a part-sectional, part-elevational front view of the transformer and casing shown in Figure 1, looking at the left-hand side.

Figure 3 is a top-plan view of the transformer and casing shown in Figures 1 and 2, but with the connecting leads in place and cover removed.

Figure 4 is a plan view of the first group of laminations laid down in building up the core and which alternates with the group of laminations shown in Figure 5.

Figure 5 is a View of the second group of laminations which alternately follows the group of laminations shown in Figure 4 as the stack is built up.

Figure 6 is a group of laminations which is inserted between the groups shown in Figures 4 and 5 at some point near the beginning of the assembly of the core, and at the end of the assembly of the core.

Figure 7 shows somewhat diagrammatically my improved core structure when used with a three-phase transformer.

Referring to the various views of the drawings, wherein like numbers refer to corresponding parts, and referring first to Figure 4, the core structure is built up of a plurality of I-shaped laminations l, 2, 3, 4, 5 and 6, of which pieces I and 2 are exactly the same; likewise 4 and 5, while the pieces 3 and 6 differ from any of the others, it being understood that these strips or laminations are of the usual transformer stock, such as silicon steel, of suitable thickness.

After the laminations shown in Figure 4 have been placed in the position indicated, the corresponding laminations, numbered with the primes, are placed over the laminations of Figure 4 in the position indicated in Figure 5, except in Figure 4 the laminations t and 5, and in Figure 5, the lamination 3, are omitted during the initial assembly, thereby leaving the central part of the core composed of the laminations 6 and 6 open for the addition of the transformer primary and secondary coils.

Interposed between the group layers of laminations just described, at some place near the beginning and. end of the stack, a special group of laminations, shown in Figure 6, is installed. This group of laminations utilizes laminations l and 2, which are the same as in Figure 4; likewise larninations 4 and 5, while laminations l and 8 are much shorter, and the lamination 9 is a special one going all the way across the stack and provided with holes Ill. The second layer of these laminations of Figure 6 is mounted alternately; that is to say, I and 8 of the second layer will change places with the laminations 4 and 5, and the laminations l and 2 will take the same position as they occupy in Figure 5. The number of layers of this special group of laminations of Figure 6 will depend on the size of the transformer; for example, in a five kva. transformer there would be three or four layers of the special group of laminations of Figure 6 near the beginning of the stack and near the end, the purpose of which will be pointed out hereinafter. It may be note-d that during the initial assembly, the laminations at one side of the special group will be omitted to correspond with the laminations previously referred to with respect to the groups shown in Figures 4 and 5.

After the stack of laminations has been. fully completed, with the exception of the omitted laminations referred to, means must then be applied to hold the laminations in position before completing the assembly. These means include first applying to the stack a pair of angle ions If and I2. These angle irons H and I2 are cut out at opposite ends to receive cross-angle irons I3 and M in interlocking relationship. The angle irons H and I2, before they are applied to the stack of laminations, are previously welded to a cross-channel l5. The channel i5 is adapted to be positioned over a block l5, preferably of metal, which is welded or otherwise securely fastened to the bottom ll of the transformer casing. In order to prevent end motion of the transformer within the casing, cross stop members 18 and i9 are anchored as by welding between the webs of the channel adjacent the block i6, so that when the transformer, after assembly is completed, is dropped into position, over the block IS, the bottom is positively positioned within the transformer casing.

After having applied the angle irons ll l2, l3 and M as indicated in the drawings (see particularly Figures 1 and 2), a bolt 20 is passed through the angle irons l3 and I4 and also through one of the holes Iii in the special group of laminations shown in Figure 6. The bolt 29 is also located in the notches 22 of the groups of laminations shown in Figures 4 and 5, to prevent angle irons l3 and I4 from sliding away from the other angle irons H and I2, and a nut 2| is drawn up so as to clamp this end of the: laminations securely in position.

After this part of the assembly operation is completed, the core is then stood on its base or at an angle of ninety degrees from the core assembly position, and then the primary and secondary windings shown collectively as 23 are placed in position over the central parts 6 and 9 of the core stack, following which the laminations which were previously omitted as heretofore described, are inserted into the positions left vacant to receive them.

Following the insertion of these top end laminations, angle irons ll, I2, I3 and I4, similar to the other angle irons II to 14 inclusive, are applied into position in substantially the same way, except that it should be mentioned that before the angle irons l l and I2 are applied, they are welded or otherwise securely fastened to a U-shaped member 24 having arms 25 and 25 extending upwardly toward the top of the casing of the transformer. Then a bolt 20' and nut 221 are applied as has been described for the corresponding parts in the bottom of the transformer. A support member 21 is fastened as by welding to the side arms 25 and 26 and carries a plate 23 which in turn supports a primary spacing block 29 and a secondary spacing block 30. The primary conductors are shown as 3| and 32 in Fig-- ure 3, while the secondary conductors are indicated by 33, 34, 35 and 36, these. conductors not being shown in Figures 1 and 2.

It will be noted that the arms 25 and 26 are each provided with a hole 31 which is adapted to receive a lag bolt 38 going into a nut 39 or equivalent thereof, welded to the side 40 of the transformer casing, thereby anchoring the top part of the transformer structure to the casing in such a way as to leave a space 4! between the arms 25 and 25 and the side walls of the casing. The arms 25 and 26 are also provided with holes 42 for the purpose of receiving a lifting hook operated by a crane or other means for lifting the entire transform-er, after it has been assembled in the manner described, to place it into the casing, and the space 4| provides room for the end of the crane hook in the hole 42. An I-bolt 45 may be attached to the cross-member 21 as a supplemental device for lifting the transformer, and in some cases brace arms 46 and 4'! may be fastened as by welding to the U-shaped memher 4, preferably at the points where the arms 25 and 26 turn upwardly. The arms 46 and 41 may be one continuous piece bent to the desired shape and fastened to the support member 21 by the I-bolt 45.

In Figure. '7, I have shown a three-phase transformer. The core for each set of windings, however, is built up the same as in the single-phase transformer just described. It will be understood, of course, that the invention is applicable to any polyphase transformer.

Since the core laminations are only clamped at the top and bottom of the stack in the manner described, there will be some small amount of spreading of the laminations between the top and bottom clamps, but this allows the impregnating varnish to run in between the laminations, thereby aiding in reducing the core losses.

From what has been said, it will be seen that I have provided a transformer which differs materially in a number of important essentials from prior art constructions with which I am familiar, and I have attained the various objects of my invention with a construction less expensive and more compact than any constructions heretofore used, and I therefore do not wish to be unduly limited in the interpretation of the appended claims.

What I claim is:

1. In 3, shell-type transformer having windings and a core composed of a stack of I-shaped laminations, interlocking angle irons surrounding the core on opposite sides of the winding and rigidly holding the core together independently of the winding, cross-member means anchoring a pair of the bottom angle irons together, a lifting strap anchoring a pair of the top angle irons together, bolts anchoring the other angle irons together at top and bottom of the stack, and strain means for preventing the angle irons from being pulled off the stack and the stack from being pulled apart comprising a plurality of laminations in the central leg of the stack and having holes therein at opposite ends thereof through which said bolts pass.

2. In a transformer having windings and a core composed of a stack of laminations, said laminations all being straight and cut so the grain of the stock runs lengthwise of each lamination, the laminations being stacked in overlapping relationship in alternate groups sothe magnetic flux travels with the grain of the stock, means for rigidly holding the core parts together independently of the windings including, at least one special strain lamination near each side of the stack and extending all the way across the stack and having a hole at each end, interlocking angle irons encircling the core on opposite sides of the windings and a bolt going through a pair of said angle irons and said lamination holes at each end of the core, the pair of angle irons at each end which cooperate with the pair of angle irons through which said bolt passes being fastened together by rigid cross-connecting means.

3. In a three-legged transformer having Windings and a core composed of a stack of I-shaped laminations, means for securely anchoring said core lamination stack together independently of said windings including; at least one special strain lamination located in the central leg of the stack near each side thereof and going all the Way across the stack and having a hole therein near each end of the lamination, interlocking metallic members encircling only the top and bottom rims of the core and a bolt going through a pair of said metallic members and said lamination holes at each end of the core, the pair of the encircling metallic members at each end of the core which cooperate with the pair of the encircling metallic members through which said bolt passes, being fastened together by rigid cross-connecting means.

4. In a transformer having windings and a core, the core being made up independently of the windings and comprising a stack of I-shaped laminations held together by metallic members themselves interlocking and encircling the top and bottom rims of the core and held in place thereto by bolts going through certain of said members and certain of said laminations at opposite ends of the core, while the bottom metallic members, which cooperate with those through which one of said bolts passes, are anchored together by a cross member having positioning stops, the bottom of the casing having a member fastened thereto to cooperate with said cross member and stops, the top metallic members, corresponding to the bottom members just mentioned, being anchored together by a U-shaped lifting and fastening strap.

5. A process of making a transformer which consists in cutting straight strips of laminations preferably so the grain runs longitudinally of the strips, certain of said strips having parts cut out to provide space for a fastening bolt, making a hole in the end of certain other strip-s cut to extend clear across the stack, assembling said strips in alternate manner in groups with said cut-outs in alignment and utilizing a few of the laminations having holes therein near the top and bottom of the stack and with the holes in alignment with said cut-outs, leaving out in the stacking operation all the laminations on one side of the stack, then applying to the side opposite to the open side metallic interlocking binding members, two of which on opposite sides of the stack have a cross anchor member carrying stops, passing a bolt through the other two of said binding members and locking the bolt in position, then turning the core so the open side is uppermost, then placing the windings in position on the core, then inserting the end laminations and then applying binding members similar to those applied at the bottom, except one pair has a lifting strap fastened thereto and passing a bolt through two of said binding members which are disposed on opposite sides of the stack and corresponding to those members through which the first-mentioned bolt passes, and then locking the bolt in position.

6. For a shell-type transformer, a core cornposed of a stack of I-shaped laminations, means independent of the winding for rigidly and securely anchoring said core stack together including, at least one special strain lamination located in the central leg of the core at each side thereof and going all the way across the stack, and having a hole therein spaced from but near each end of the lamination, certain of the regular laminations having parts out out in alignment with the central leg to provide a passageway for bolts going through said strain laminations, interlocking angle irons encircling the core on opposite ends only, a bolt at each end of the core going through a pair of said angle irons and said strain laminations, the pair of angle irons at each end which cooperate with the pair of angle irons through which said bolt passes, being fastened together by rigid cross-connecting means.

'7, A transformer core structure as set forth in claim 6, further characterized in that the fastening means between the said top complementary angle irons is in the form of a U-shaped strap for lifting the core structure.

8. For a shell-type transformer, a core composed of straight laminations stacked in overlapping relationship in alternate groups with at least one special group of flux-carrying laminations, of the same thickness as the other laminations, near each side of the central leg of the stack, at least one lamination in the central leg of each special oppositely disposed group going clear across the stack and having a bolt hole near each end, angle irons encircling the core at opposite ends, one pair of said irons at each end of the core being fastened together by crossconnecting means, the other pair of angle irons at each end of the core interlocking with the first-mentioned pair and provided with centrally located holes and a clamping bolt going through said holes in said angle irons as well as through said lamination holes.

JOHN R. GASTON. 

